U.S. patent application number 13/467483 was filed with the patent office on 2012-11-15 for transmission apparatus and method for serial and parallel channel interworking in optical transport network.
This patent application is currently assigned to Electronics and Telecommunications Research Institute. Invention is credited to Jong-Ho KIM, Jong-Yoon SHIN, Ji-Wook YOUN.
Application Number | 20120288277 13/467483 |
Document ID | / |
Family ID | 47141969 |
Filed Date | 2012-11-15 |
United States Patent
Application |
20120288277 |
Kind Code |
A1 |
SHIN; Jong-Yoon ; et
al. |
November 15, 2012 |
TRANSMISSION APPARATUS AND METHOD FOR SERIAL AND PARALLEL CHANNEL
INTERWORKING IN OPTICAL TRANSPORT NETWORK
Abstract
A transmission apparatus and method for serial and parallel
channel interworking in an optical transport network are provided.
The transmission apparatus for serial and parallel channel
interworking ensures interworking between parallel optical modules
or between parallel and serial optical modules, regardless of a
protocol, without having to add logics or with only a minimum
number of logics, in order to manufacture a small-size optical
module with low power consumption.
Inventors: |
SHIN; Jong-Yoon;
(Daejeon-si, KR) ; KIM; Jong-Ho; (Daejeon-si,
KR) ; YOUN; Ji-Wook; (Daejeon-si, KR) |
Assignee: |
Electronics and Telecommunications
Research Institute
Daejeon-si
KR
|
Family ID: |
47141969 |
Appl. No.: |
13/467483 |
Filed: |
May 9, 2012 |
Current U.S.
Class: |
398/45 |
Current CPC
Class: |
H04J 3/1664 20130101;
H04J 2203/006 20130101; H04J 3/047 20130101; H04J 3/14 20130101;
H04L 25/14 20130101; H04J 3/0608 20130101 |
Class at
Publication: |
398/45 |
International
Class: |
H04B 10/20 20060101
H04B010/20; H04J 14/00 20060101 H04J014/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 9, 2011 |
KR |
10-2011-0043557 |
Apr 27, 2012 |
KR |
10-2012-0044924 |
Claims
1. A transmission apparatus for serial and parallel channel
interworking, which supports signal comparability between a serial
channel signal and a parallel channel signal in an optical
transport network, the transmission apparatus comprising: a first
interface unit including first receiving (RX) and transmitting (TX)
interface units configured to operate in a serial interface TX mode
for channel interworking transmission between serial optical
modules supporting a SerDes Framer Interface (SFI) and to process
data signals and deskew signals that are transmitted in a
transmission order of frames; and a second interface unit including
second RX and TX interface units configured to operate in a
parallel interface TX mode and to process data signals that are
transmitted through a plurality of data lanes for channel
interworking transmission between the serial optical modules
supporting no SFI or between parallel optical modules supporting no
SFI.
2. The transmission apparatus of claim 1, wherein a serial optical
module which supports or does not supports a SFI-5.2 is a 40
GBASE-FR optical module, a serial optical module which supports the
SFI-5.2 is a 40 G 300 pin MSA optical module, and a parallel
optical module which does not support the SFI is a 40 GBASE-LR
optical module.
3. The transmission apparatus of claim 1, wherein the serial
interface TX mode of the first interface unit is a mode that
supports serial channel signal transmission using a SFI-5, and the
parallel interface TX mode of the second interface unit is a mode
that supports parallel channel signal transmission using a
plurality of parallel data lanes.
4. The transmission apparatus of claim 1, further comprising a
decoding unit configured to monitor the serial interface TX mode of
the first interface unit and the parallel interface TX mode of the
second interface unit to thereby determine whether to activate the
first interface unit or the second interface unit.
5. The transmission apparatus of claim 4, wherein the decoding unit
automatically converts a transmission mode into one of the serial
interface TX mode and the parallel interface TX mode according to a
received input signal.
6. The transmission apparatus of claim 5, wherein the decoding unit
activates, if receiving a Loss of Lane Alignment (LOL) alarm signal
from the second RX interface unit, the first RX interface unit, the
decoding unit deactivates, if receiving no RX Out-of-Alignment
(RXOOA) alarm signal when the first RX interface unit is activated,
the second RX interface unit, and the decoding unit deactivates, if
receiving no LOL alarm signal from the second RX interface unit and
receiving a RXOOA alarm signal from the first RX interface unit
when the first RX interface unit is activated, the first RX
interface unit and activates the second RX interface unit.
7. The transmission apparatus of claim 5, wherein the decoding unit
activates, if receiving a LOL alarm signal from the second RX
interface unit, the first RX interface unit or a RX deskew channel
signal receiver in the first RX interface unit, the decoding unit
activates, if receiving no Loss of Frame (LOF) alarm signal from
the first RX interface unit or the RX deskew channel signal
receiver in the first RX interface unit, the first RX interface
unit, and the decoding unit activates, if receiving no RXOOA alarm
signal from the first RX interface unit when the first RX interface
unit is activated, the first TX interface unit and deactivates the
second TX and RX interface units.
8. A transmission apparatus for serial and parallel channel
interworking, which supports signal comparability between serial
and parallel channel signals in an optical transport network, the
transmission apparatus comprising a Receiving (RX) interface unit,
wherein the RX interface unit comprises a plurality of OTU3
demultiplexing lane receivers configured to receive a plurality of
lane data signals from a serial optical module which does not
support the SFI and to detect an OTU3 demultiplexing pattern from
the plurality of lane data signals, if data signals transmitted
from a serial optical module which supports the SFI are
demultiplexed through the serial optical module which does not
support the SFI for channel interworking between the serial optical
module which supports the SFI and the serial optical module which
does not support the SFI, a plurality of RX delay units configured
to delay outputs of the data signals transmitted from the plurality
of OUT3 demultiplexing lane receivers, and a lane alignment unit
configured to align data signals according to the demultiplexing
pattern detected by the plurality of OTU3 demultiplexing lane
receivers.
9. The transmission apparatus of claim 8, wherein the serial
optical module which does not support the SFI is a 40 GBASE-FR
optical module, and the serial optical module which supports the
SFI is a 40 G 300 pin MSA optical module.
10. The transmission apparatus of claim 8, wherein the RX interface
unit further comprises an OTU3 demultiplexing deskew controller
configured to generate timing signals for minimizing delays in data
outputs of the delay units, based on timings at which OTU3
demultiplexing patterns of the individual lanes have been detected,
received from the individual OTU3 demultiplexing lane receivers, to
decide an order of the lanes using pattern information indicating
which pattern has been detected from each lane, and to generate
lane realignment information according to the decided order of the
lanes.
11. The transmission apparatus of claim 8, wherein the RX interface
unit further comprises a RX lane rotator configured to provide a
bypass function for selectively operating one RX mode of a serial
interface RX mode and a parallel interface RX mode.
12. The transmission apparatus of claim 8, further comprising a TX
interface unit including a plurality of TX delay units configured
to compensate for a TX skew generated between the transmission
apparatus and a multiplexer of the serial optical module that does
not support the SFI.
13. The transmission apparatus of claim 12, further comprising a TX
pre-skew controller configured to adjust TX delays of the plurality
of TX delay units using information received from the plurality of
OTU3 demultiplexing lane receivers in order to compensate for the
TX skew.
14. The transmission apparatus of claim 13, wherein the RX
interface unit fixes the plurality of RX delay units and operates
the TX pre-skew controller while compensating for the TX skew.
15. The transmission apparatus of claim 13, wherein the RX
interface unit further comprises a PseudoRandom Binary Sequence
(PRBS) or an iterative pattern to compensate for a RX skew for each
lane, wherein the PRBS or the iterative pattern is generated by the
serial optical module which does not support the SFI.
16. A transmission method for serial and parallel channel
interworking of a transmission apparatus for serial and parallel
channel interworking, the transmission apparatus supporting signal
comparability between a serial channel signal and a parallel
channel signal in an optical transport network, the transmission
method comprising at least one operation of: processing data
signals and deskew signals that are transmitted in a transmission
order of frames, in a serial interface transmission mode, through a
first interface unit including first transmitting and receiving
interface units for channel interworking transmission between
serial optical modules that support a SerDes Framer Interface
(SFI); and processing data signals transmitted through a plurality
of data lanes, in a parallel interface transmission mode, through a
second interface unit including second transmission and reception
interfaces for channel interworking transmission between the serial
optical modules that do not support the SFI or between parallel
optical modules that do not support the SFI.
17. The transmission method of claim 16, further comprising
automatically converting a transmission mode into one of a serial
interface transmission mode and a parallel interface transmission
mode according to a received signal.
18. The transmission method of claim 17, wherein the automatically
converting of the transmission mode into one of the serial and
parallel interface transmission modes comprises: if a Loss of Lane
Alignment (LOL) alarm signal is generated from the second receiving
interface unit and no RX Out-of-Alignment (RXOOA) alarm signal is
generated when the first receiving interface unit is activated,
activating the first receiving interface unit, and deactivating the
second receiving interface unit; and if no LOL alarm signal is
generated from the second receiving interface unit and a RXOOA
alarm signal is generated from the first receiving interface unit
when the first receiving interface unit is activated, deactivating
the first receiving interface unit, and activating the second
receiving interface unit.
19. A transmission method for serial and parallel channel
interworking of a transmission apparatus for serial and parallel
channel interworking, the transmission apparatus supporting signal
comparability between a serial channel signal and a parallel
channel signal in an optical transport network, the transmission
method comprising: if data signals transmitted from a serial
optical module which supports a SerDes Framer Interface (SFI) are
demultiplexed through a serial optical module which does not
support the SFI for channel interworking between the serial optical
module which supports the SFI and the serial optical module which
does not support the SFI, receiving a plurality of lane data
signals from the serial optical module that does not support the
SFI, and detecting an OTU3 demultiplexing pattern from the
plurality of lane data signals to compensate for receiving skews of
the lane data signals; and aligning the plurality of data signals
according to the demultiplexing pattern.
20. The transmission method of claim 19, further comprising
compensating for transmission skews between the transmitting
apparatus and a multiplexer of the serial optical module which does
not support the SFI.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(a) of Korean Patent Applications No. 10-2011-0043557,
filed on May 9, 2011, and No. 10-2012-0044924, filed on Apr. 27,
2012, the entire disclosures of which are incorporated herein by
reference for all purposes.
BACKGROUND
[0002] 1. Field
[0003] The following description relates to a technique for optical
transmission in an optical transport network, and more
particularly, to a transmission technique for serial and parallel
channel interworking to support signal comparability between serial
and parallel channel signals in an optical transport network.
[0004] 2. Description of the Related Art
[0005] ITU-T (International Telecommunications
Union-Telecommunication) G.693 defines NRZ 10 G and 40 G optical
signal specifications for communication between offices in a
maximally 20 km radius. In particular, G.693 defines VSR2000-3R2
which is one of NRZ 40 G optical signal specifications having a
transmission distance of 2 km using a wavelength of 1550 nm. A 40 G
300 pin Multi Source Agreement (MSA) optical module is used as a
NRZ 40 G serial optical module that satisfies a VSR2000-3R2
specification.
[0006] The 40 G 300 pin MSA optical module defined in 40 G 300 pin
MSA uses SerDes Framer Interface (SFI)-5.1 as an OIF standard for
connection to a framer or a Forward Error Correction (FEC)
processor. The OIF SFI-5.1 defines a deskew channel for
compensating for skews between 16 2.5 G-level data signals, as well
as compensating for the 16 2.5 G-level data signals.
[0007] Meanwhile, the IEEE 802.3ba standard introduces a Multi-Lane
Distribution (MLD) method to a Physical Coding Sub-layer (PCS) so
that a 40 G Ethernet signal can be all transmitted through four,
two or one physical lane, and also defines 40 GBASE-LR4 PMD as a
physical standard for transmitting 40 G Ethernet signals. The 40
GBASE-LR4 PMD uses, instead of transmitting a 40 G Ethernet signal
as a single serial optical signal, a method of assigning different
Coarse Wavelength Division Multiplexing (CWDM) wavelengths to four
10 G lanes and performing WDM.
[0008] As described above, the 40 GBASE-LR4 PMD has an optical
signal specification that is different from the VSR2000-3R2. In
order to satisfy the 40 GBASE-LR4 PMD optical specification, since
a pluggable type of optical module whose specification is different
from the VSR2000-3R2 is required due to the characteristics of the
Ethernet, a 40 G CFP optical module or a 40 G Ethernet QSFP+
optical module that are different from the conventional 40 G 300
pin MSA optical module have been released.
[0009] However, in order for the 40 G-level optical module to have
price competitiveness and a large supply, like a 10 G-level XFP
optical module, it is important to standardize an optical module
that can be used in all the 10 G Ethernet, 10 G SDH, and 10 G OTN.
Accordingly, the IEEE 802.3 configures an IEEE 802.3bg Task force
to complete standardization of 40 GBASE-FR PMD that is compatible
with the VSR2000-3R2 being a NRZ serial 40 G standard that was the
existing optical signal specification for 40 G SDH and 40 G
OTN.
[0010] An initially developed 40 GBASE-FR PMD is expected to
support comparability with the existing 40 G 300 pin MSA optical
module. Accordingly, equipment vendors use a 40 G 300 pin MSA
optical module to receive all 40 G SDH, 40 G OTN, and 40 G Ethernet
signals. However, with the progression of technology, a pluggable
type of 40BASE-FR PMD optical module having a size smaller than a
fixed type of 40 G 300 pin MSA optical module and low power
consumption is expected to be released in near future. Since the 40
G Ethernet can connect optical modules to each other through four
electrical signals using a PCS lane distribution method, it is not
preferable to use a SFI-5.1 interface that increases power
consumption and has a large volume, and it is efficient to
configure an optical module with a 4:1 multiplexer and a 1:4
demultiplexer.
SUMMARY
[0011] The following description relates to a transmission
apparatus and method for serial and parallel channel interworking
to implement signal comparability between 40 G SDH signals and 40 G
OTN signals regardless of a protocol without having to add logics
or with only a minimum number of logics in order to manufacture a
small-size optical module with low power consumption.
[0012] In one general aspect, there is provided a transmission
apparatus for serial and parallel channel interworking, which
supports signal comparability between a serial channel signal and a
parallel channel signal in an optical transport network, the
transmission apparatus including: a first interface unit including
first receiving (RX) and transmitting (TX) interface units
configured to operate in a serial interface TX mode for channel
interworking transmission between serial optical modules supporting
a SerDes Framer Interface (SFI) and to process data signals and
deskew signals that are transmitted in a transmission order of
frames; and a second interface unit including second RX and TX
interface units configured to operate in a parallel interface TX
mode and to process data signals that are transmitted through a
plurality of data lanes for channel interworking transmission
between the serial optical modules supporting the SFI or between
parallel optical modules supporting no SFI.
[0013] In another general aspect, there is provided a transmission
apparatus for serial and parallel channel interworking, which
supports signal comparability between serial and parallel channel
signals in an optical transport network, the transmission apparatus
including a Receiving (RX) interface unit, wherein the RX interface
unit comprises a plurality of OTU3 demultiplexing lane receivers
configured to receive a plurality of lane data signals from a
serial optical module which does not support the SFI and to detect
an OTU3 demultiplexing pattern from the plurality of land data
signals, if data signals transmitted from a serial optical module
which supports the SFI are demultiplexed through the serial optical
module which does not support the SFI for channel interworking
between the serial optical module which supports the SFI and the
serial optical module which does not support the SFI, a plurality
of RX delay units configured to delay outputs of the data signals
transmitted from the plurality of OUT3 demultiplexing lane
receivers, and a lane alignment unit configured to align data
signals according to the demultiplexing pattern detected by the
plurality of OTU3 demultiplexing lane receivers.
[0014] In another general aspect, there is provided a transmission
method for serial and parallel channel interworking of a
transmission apparatus for serial and parallel channel
interworking, the transmission apparatus supporting signal
comparability between a serial channel signal and a parallel
channel signal in an optical transport network, the transmission
method including at least one operation of: processing data signals
and deskew signals that are transmitted in a transmission order of
frames, in a serial interface transmission mode, through a first
interface unit including first transmitting and receiving interface
units for channel interworking transmission between serial optical
modules that support a SerDes Framer Interface (SFI); and
processing data signals transmitted through a plurality of data
lanes, in a parallel interface transmission mode, through a second
interface unit including second transmission and reception
interfaces for channel interworking transmission between the serial
optical modules that do not support the SFI or between parallel
optical modules that do not support the SFI.
[0015] In another general aspect, there is provided a transmission
method for serial and parallel channel interworking of a
transmission apparatus for serial and parallel channel
interworking, the transmission apparatus supporting signal
comparability between a serial channel signal and a parallel
channel signal in an optical transport network, the transmission
method including: if data signals transmitted from a serial optical
module which supports a SerDes Framer Interface (SFI) are
demultiplexed through a serial optical module which does not
support the SFI for channel interworking between the serial optical
module which supports the SFI and the serial optical module which
does not support the SFI, receiving a plurality of lane data
signals from the serial optical module that does not support the
SFI, and detecting an OTU3 demultiplexing pattern from the
plurality of lane data signals to compensate for receiving skews of
the lane data signals; and aligning the plurality of data signals
according to the demultiplexing pattern.
[0016] Other features and aspects will be apparent from the
following detailed description, the drawings, and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a view for explaining Multi-Lane Distribution
(MLD).
[0018] FIGS. 2A and 2B are views for explaining problems regarding
interworking between optical modules.
[0019] FIG. 3 is a diagram illustrating an example of a
transmission apparatus for 40 G serial and parallel channel
interworking, which supports a SerDes Framer Interface (SFI)-5.2
interface.
[0020] FIG. 4 is a diagram illustrating another example of a
transmission apparatus for 40 G serial and parallel channel
interworking, which supports a SerDes Framer Interface (SFI)-5.2
interface.
[0021] FIG. 5 is a diagram illustrating another example of a
transmission apparatus for 40 G serial and parallel channel
interworking, which supports a SerDes Framer Interface (SFI)-5.2
interface.
[0022] FIGS. 6A and 6B are flowcharts illustrating a method in
which the transmission apparatus of FIG. 5 performs mode conversion
between an OTL3.4 interface mode and a SFI-5.2 interface mode
according to a type of a received signal.
[0023] FIG. 7 is a diagram illustrating a 40 G OTL3.4 RX interface
of a general transmission apparatus for serial and parallel channel
interworking that interfaces a 40 GBASE-FR optical module.
[0024] FIG. 8 shows four data signal streams that are generated by
1:4 demultiplexing of a serial OTU3 signal.
[0025] FIG. 9 is a diagram illustrating a configuration example of
a receiver of a transmission apparatus for 40 G serial and parallel
channel interworking that does not support the SFI-5.2
interface.
[0026] FIG. 10 is a diagram illustrating another configuration
example of a receiver of a transmission apparatus for 40 G serial
and parallel channel interworking that does not support the SFI-5.2
interface.
[0027] FIG. 11 is a diagram illustrating a configuration example of
a transceiver of a transmission apparatus for 40 G serial and
parallel channel interworking that does not support the SFI-5.2
interface.
[0028] FIG. 12 is a diagram illustrating another configuration
example of a transceiver of a transmission apparatus for 40 G
serial and parallel channel interworking that does not support the
SFI-5.2 interface.
[0029] Throughout the drawings and the detailed description, unless
otherwise described, the same drawing reference numerals will be
understood to refer to the same elements, features, and structures.
The relative size and depiction of these elements may be
exaggerated for clarity, illustration, and convenience.
DETAILED DESCRIPTION
[0030] The following description is provided to assist the reader
in gaining a comprehensive understanding of the methods,
apparatuses, and/or systems described herein. Accordingly, various
changes, modifications, and equivalents of the methods,
apparatuses, and/or systems described herein will be suggested to
those of ordinary skill in the art. Also, descriptions of
well-known functions and constructions may be omitted for increased
clarity and conciseness.
[0031] FIG. 1 is a view for explaining Multi-Lane Distribution
(MLD).
[0032] ITU-T applies MLD for transmitting OTU3 (Optical Transport
Unit 3) signals through four physical lanes, to OTU3 frames, in
order to transmit OTU3 signals that are one kind of 40 G OTN
(Optical Transport Network) signals using four CWDM wavelengths
through a 40 GBASE-LR4 optical module for Ethernet. FIG. 1 shows an
example of transmitting a 40 G OTU3 signal through 4-lane
distribution. The OTU3 signal transmission through 4-lane
distribution is referred to as OTL3.4 transmission.
[0033] Conventionally, a 40 G 300 pin MSA optical module has been
used to transmit OTU3 signals, and a 40 GBASE-LR4 PMD optical
module and a 40 GBASE-FR PMD optical module that will be released
in near future although their types have not yet been decided also
will be able to be used to transmit OTU3 signals. The 40 GBASE-FR
PMD optical module, which is basically aimed at transmitting 40 G
Ethernet signals, may transmit OTU3 signals using an OTL3.4
transmission method which is a 4-lane distribution method as
illustrated in FIG. 1. However, since the 40 GBASE-FR PMD optical
module does not support a conventional OTU3 transmission method of
transmitting and receiving OTU3 frames in the order which they have
been transmitted, the 40 GBASE-FR PMD optical module cannot
interwork with the 40 G 300 pin MSA optical module although the
same optical signal specification is used. Accordingly, the present
invention has been proposed to solve a problem regarding
interworking between the 40 GBASE-FR PMD optical module which is a
parallel optical module and the 40 G 300 pin MSA optical module
which is a serial optical module.
[0034] FIGS. 2A and 2B are views for explaining problems regarding
interworking between optical modules.
[0035] FIG. 2A shows the case where two 40 GBASE-FR PMD optical
modules interface with each other. The 40 GBASE-FR PMD optical
modules interface with each other using the OTL3.4 transmission
method. Since the 40 GBASE-FR PMD optical module has a simple
configuration consisting of a 4:1 multiplexer (MUX) and a 1:4
demultiplexer (DEMUX), skews are generated in four data lanes
connected to a framer or a Forward Error Correction (FEC)
processor, and accordingly, it is impossible to transmit OTU3
signals in the order which they have been transmitted. However, if
both the 40 GBASE-FR PMD optical modules use the OTL3.4
transmission method, the 40 GBASE-FR PMD optical modules can
communicate with each other without causing any problem. The OTL3.4
transmission method transmits OTU3 signals through 4-lane
distribution, as described above with reference to FIG. 1.
[0036] FIG. 2B shows the case where a 40 GBASE-FR PMD optical
module interfaces with a 40 G 300 pin MSA optical module.
Generally, interfacing between a 40 GBASE-FR PMD optical module and
a 40 G 300 pin MSA optical module is impossible. Even when an
optical signal specification has been standardized such that a 40
GBASE-FR PMD optical module can interwork with a 40 G 300 pin MSA
optical module, the 40 GBASE-FR PMD optical module still has to use
the OTL3.4 transmission method, and the 40 G 300 pin MSA optical
module has to use the OTU3 transmission method. The OTU3
transmission method transmits OTU3 signals in the order which they
have been transmitted. For this reason, in spite of standardization
of optical signal specification, the 40 GBASE-FR PMD optical module
cannot interwork with the 40 G 300 pin MSA optical module. As such,
40 G SDH and 40 G OTN signals that can be transmitted through the
40 G 300 pin MSA optical module interwork with the 40 GBASE-FR
optical module only on optical signal specification, not on
protocol.
[0037] In order to overcome the problem, a method of enabling the
40 G multiplexer and 40 G demultiplexer of the 40 GBASE-FR PMD
optical module to convert the OTL3.4 transmission method into the
OTU3 transmission method has been proposed. However, the method is
protocol-dependent, and accordingly, a separate signal converter
for transmitting 40 G SDH signals is needed, which is a roadblock
to fabrication of a small-size 40 GBASE-FR PMD optical module with
low power consumption.
[0038] In order to solve the problem, there are provided a
transmission apparatus and method for serial and parallel channel
interworking to implement signal comparability between 40 G SDH
signals and 40 G OTN signals, regardless of a protocol, without
having to add logics or with only a minimum number of logics, in
order to manufacture a small-size optical module with low power
consumption.
[0039] FIG. 3 is a diagram illustrating an example of a
transmission apparatus 1a for 40 G serial and parallel channel
interworking, which supports a SFI-5.2 interface.
[0040] Referring to FIG. 3, the transmission apparatus 1a includes
a SFI-5.2 interface unit, an OTL3.4 interface unit, a receiving
(RX) interface selector 12, and a transmitting (TX) interface
selector 15.
[0041] The SFI-5.2 interface unit includes a SFI-5.2 RX interface
unit 10 and a SFI-5.2 TX interface unit 13. The OTL3.4 interface
unit includes an OTL3.4 RX interface unit 11 and an OTL3.4 TX
interface unit 14.
[0042] The RX interface selector 12 selects one from an OTU3 frame
signal output from the SFI-5.2 RX interface unit 10 and an OTU3
frame signal output from the OTL3.4 RX interface unit 11. The TX
interface selector 15 selects one from an OTU3 frame signal output
from the SFI-5.2 TX interface unit 13 and an OTL3.4 TX signal
output from the OTL3.4 TX interface unit 14. Here, the OTU3 frame
signal is a signal that is transmitted in the transmission order of
OTU3 frames, and the OTL3.4 TX signal is a signal resulting from
distributing OTU3 frames into four multi lanes.
[0043] A core logic unit 16 is used to process OTU3 signals. The
transmission apparatus 1a receives OTU3 signals from the core logic
unit 16 through the SFI-5.2 TX interface unit 13 and the OTL3.4 TX
interface unit 14, and transmits OTU3 signals selected by the RX
interface selector 12 to the core logic unit 16.
[0044] The transmission apparatus 1a may be a framer or a FEC
processor. According to an example, a 40 GBASE-FR PMD optical
module may use a SFI-5.2 to interface with a 40 G 300 pin MSA
optical module. The SFI-5.2 which is an OIF standard enables a
framer and SerDes to interface with four 10 G data lanes,
regardless of a protocol. For this, the OIF SFI-5.2 defines four 10
G-level data signals, and additionally defines a deskew channel for
compensating for skews between the four 10 G-level data signals.
That is, five physical lanes are needed, the multiplexer and
demultiplexer of the optical module each needs an optical
transceiver for receiving and transmitting deskew signals, and
additionally, a logic for aligning the skews of data signals
received through the deskew channel and a logic for generating a
deskew channel from output data signals may be needed.
[0045] The configuration of the transmission apparatus 1a which is
connected to the 40 GBASE-FR PMD optical module supporting the
SFI-5.2 interface is shown in FIG. 3.
[0046] In order to connect the 40 GBASE-FR PMD optical module to
the 40 G 300 pin MSA optical module, the transmission apparatus 1a
connects the 40 GBASE-FR optical module to the 40 G 300 pin MSA
optical module in the transmission order of OTU3 frames through the
SFI-5.2 interface, instead of outputting an OTL3.4 signal.
[0047] For example, if four 10 G data signals are input to the 40
GBASE-FR optical module supporting the SFI-5.2 interface, the 40
GBASE-FR optical module uses the deskew channel to compensate for
skews generated between four 10 G data signals that are transmitted
between the transmission apparatus 1a and the 40 GBASE-FR optical
module. Successively, the 40 GBASE-FR optical module multiplexes
the four 10 G data signals to an optical signal through a 4:1
multiplexer and outputs the optical signal to the 40 G 300 pin MSA
optical module, thereby interworking with the 40 G 300 pin MSA
optical module.
[0048] The 40 GBASE-FR optical module can perform the inverse
operation in the same way. That is, if receiving a 40 G serial
channel signal from the 40 G 300 pin MSA optical module in the
transmission order of OTU3 frames, the 40 GBASE-FR optical module
demultiplexes the 40 G serial channel signal into four 10 G data
signals through a 1:4 demultiplexer, adds a deskew channel signal
to the four 10 G data signals, and transfers the resultant signal
to the transmission apparatus 1a. Then, the transmission apparatus
1a compensates for the skews of the four data signals received from
the 40 G 300 pin MSA optical module through the deskew channel so
as to completely receive OTU3 frame signals, and accordingly, the
transmission apparatus 1a can interwork with the 40 G 300 pin MSA
optical module.
[0049] Meanwhile, in order to connect the 40 GBASE-FR PMD optical
module supporting the SFI-5.2 interface to the 40 G 300 pin MSA
optical module, the transmission apparatus 1a has to operate,
instead of by an OTL3.4 transmission method, by an OUT3
transmission method that receives and transmits OTU3 frame signals
as they are. Meanwhile, in the case of connecting a 40 GBASE-FR
optical module to another 40 GBASE-FR optical module, it is more
efficient that a 40 GBASE-FR optical module communicates with
another 40 GBASE-FR optical module using only four data signals,
than using a SFI-5.2 interface by generating a separate deskew
channel, since power consumption can be reduced. Also, since a
pluggable type of 40 GBASE-FR optical module does not support the
SFI-5.2 interface, the pluggable-type of 40 GBASE-FR optical module
cannot transmit signals using the OUT3 transmission method.
Accordingly, in the case of replacing a 40 GBASE-FR optical module
with a 40 GBASE-LR4 optical module, OTL3.4 transmission has to be
used.
[0050] Consequently, when a 40 G 300 pin MSA optical module
interfaces with a 40 GBASE-FR optical module supporting a SFI-5.2
interface, the transmission apparatus 1a and the 40 GBASE-FR
optical module operate in a SFI-5.2 interface mode, and when a 40
GBASE-FR optical module supporting a SFI-5.2 interface interfaces
with another optical module that is different from a 40 G 300 pin
MSA optical module, the transmission apparatus 1a and the 40
GBASE-FR optical module operate in the OTL3.4 transmission mode so
that the transmission apparatus 1a and the 40 GBASE-FR optical
module use only a multiplex function and a demultiplex
function.
[0051] However, it is inconvenient that what type of optical module
of the other party is connected to a user has to be recognized and
the transmission mode has to be manually converted according to the
recognized optical module type of the other party although the 40
GBASE-FR optical module supports the SFI-5.2 interface. That is, it
is most efficient that if the other party's optical module is a 40
GBASE-FR optical module, the transmission mode is converted into
the OTL3.4 interface mode, if the other party's optical module is a
40 G 300 PIN MSA optical module, the transmission mode is converted
into the SFI-5.2 interface mode, and if the other party's optical
module is a 40 GBASE-LR4 optical module, the transmission mode is
converted into the OTL3.4 interface mode. A transmission apparatus
1b for 40 G serial and parallel channel interworking, which
includes a component for overcoming the problem, will be described
with reference to FIG. 4, below.
[0052] FIG. 4 is a diagram illustrating another example of a
transmission apparatus 1b for 40 G serial and parallel channel
interworking, which supports the SFI-5.2 interface.
[0053] Referring to FIG. 4, the transmission apparatus 1b further
includes a decoding unit 17 in addition to the components of the
transmission apparatus 1a shown in FIG. 3.
[0054] The decoding unit 17 decides a reception mode using a Loss
of Lane Alignment (LOL) alarm signal indicating whether or not an
OTL3.4 signal received through an OTL3.4 RX interface unit 11 has
been normally aligned, and a RXOOA (RX Out-of-Alignment) alarm
signal indicating whether or not a SFI-5.2 RX interface 10 has
normally aligned a SFI-5.2 signal.
[0055] For example, if a LOL alarm signal is activated and a RXOOA
alarm signal is deactivated, the decoding unit 17 determines that
the SFI-5.2 RX interface unit 10 normally operates to enable a RX
interface selector 12 to select data aligned by the SFI-5.2 RX
interface unit 10. Also, the decoding unit 17 enables a
transmission interface selector 15 to select a data signal output
from a SFI-5.2 transmission interface unit 13 so that signals are
transmitted through the SFI-5.2 transmission interface unit 13
instead of an OTL3.4 transmission interface unit 14. The SFI-5.2
transmission interface 13 outputs a deskew channel data signal.
[0056] FIG. 5 is a diagram illustrating another example of a
transmission apparatus 1c for 40 G serial and parallel channel
interworking, which supports a SFI-5.2 interface.
[0057] Since the transmission apparatus 1c can operate through one
of an OTL3.4 interface unit and a SFI-5.2 interface unit, it is
inefficient to always operate both the OTL3.4 interface unit and
the SFI-5.2 interface unit. The transmission apparatus 1c shown in
FIG. 5 is an example designed to efficiently use power by improving
inefficiency.
[0058] Referring to FIG. 5, according to an example, initially,
OTL3.4 RX and TX interface units 11 and 14 are activated, and
SFI-5.2 RX and TX interface units 10 and 13 are deactivated. If a
decoding unit 17 receives a LOL alarm signal indicating that an
OTL3.4 signal has not been normally aligned from an OTL RX
interface unit 11, the decoding unit 17 activates the SFI-5.2 RX
interface unit 10 or a RXDSC signal receiver included in the
SFI-5.2 RX interface unit 10. If the SFI-5.2 RX interface unit 10
is activated, whether or not a SFI-5.2 signal has been normally
aligned may be checked by receiving a RXOOA alarm signal. If no
RXOOA alarm signal is received, the SFI-5.2 RX interface unit 10
may determine that a SFI-5.2 signal has been normally aligned, and
accordingly the OTL3.4 RX interface unit 11 may be deactivated.
Simultaneously, the OTL3.4 TX interface unit 14 is deactivated and
the SFI-5.2 TX interface unit 13 is activated so that the
transmission mode is converted into a SFI-5.2 interface mode, and
accordingly, the transmission apparatus 1c can connect to the
existing 40 G 300 pin MSA optical module. At this time, if the
component of the transmission apparatus 1c is implemented as ASIC,
power consumption can be reduced by deactivating the corresponding
logic. If the component is implemented as a Field Programmable Gate
Array (FPGA), the corresponding logic may be reconfigured such that
one logic of the OTL3.4 RX and TX interface units 11 and 14 and the
SFI-5.2 RX and TX interface units 10 and 13 is activated.
[0059] FIGS. 6A and 6B are flowcharts illustrating a method in
which the transmission apparatus 1c of FIG. 5 performs mode
conversion between an OTL3.4 interface mode and a SFI-5.2 interface
mode according to a type of a received signal.
[0060] Referring to FIGS. 5, 6A, and 6B, the OTL3.4 RX and TX
interface units 11 and 14 are first activated (600). Meanwhile, in
order to first activate the SFI-5.2 RX and TX interface units 10
and 13, the process starts from operation B.
[0061] Successively, the decoding unit 17 of the transmission
apparatus 1c determines whether a LOL alarm signal is output from
the OTL3.4 RX interface unit 11 (610). If no LOL alarm signal is
generated, the decoding unit 17 reports an OTL3.4 interface mode to
the core logic unit 16 (670) and continues to determine whether a
LOL alarm signal is generated. Meanwhile, if a LOL alarm signal is
generated, the decoding unit 17 determines that OTL3.4 reception
does not normally operate. Accordingly, the decoding unit 17
activates the SFI-5.2 RX interface unit 10, specifically, only a
RXDSC receiver of the SFI-5.2 RX interface unit 10 as possible
(620). In the current example, it is assumed that activating only
the RXDSC receiver of the SFI-5.2 RX interface unit 10 is
possible.
[0062] Successively, the decoding unit 17 determines whether a LOF
alarm signal is output from the RXDSC receiver of the SFI-5.2 RX
interface unit 10 (630). If no LOF alarm signal is generated, the
decoding unit 17 determines that a RXDSC (reception deskew) signal
is normally received, activates the SFI-5.2 RX interface unit 10,
and determines whether an RXOOZ alarm signal is generated by the
SFI-5.2 RX interface unit 10 (650). If no RXOOA alarm signal is
generated, the decoding unit 17 determines that a SFI-5.2 RX
interface signal is normally received, activates the SFI-5.2 TX
interface unit 13 and deactivates the OTL3.4 RX and TX interface
units 11 and 14 to thereby change data paths connected to the
OTL3.4 RX and TX interface units 11 and 14 to the SFI-5.2 RX and TX
interface units 10 and 13, respectively.
[0063] Meanwhile, if a LOF alarm signal is generated in operation
630, the decoding unit 17 determines that RXDSC reception does not
normally operate and again checks a LOL alarm signal output from
the OTL3.4 RX interface unit 11 (730). At this time, if no LOL
alarm signal is generated, the decoding unit 17 deactivates the
RXDSC receiver of the SFI-5.2 RX interface unit 10 (760).
Meanwhile, if a LOL alarm signal is generated and no LOF alarm
signal is generated, the decoding unit 17 activates the SFI-5.2 RX
interface unit 10 (640). If both LOL and LOF alarm signals are
generated, the decoding unit 17 reports a reception error state to
the core logic unit 16 (750) and continues to determine whether LOL
and LOF alarm signals are generated.
[0064] Meanwhile, if a RXOOA alarm signal is generated in operation
650, since it means that the SFI-5.2 RX interface unit 10 does not
normally operate, the decoding unit 17 again checks a LOL alarm
signal output from the OTL3.4 RX interface unit 11 (830). If no LOL
alarm signal is generated, the decoding unit 17 deactivates the
SFI-5.2 RX interface unit 10 (860). Meanwhile, if a LOL alarm
signal is generated and no RXOOA alarm signal is generated in
operation 840, the decoding unit 17 activates the SFI-5.2 RX
interface unit 13 (660). If a LOL alarm signal is generated and a
RXOOA alarm signal is generated in operation 840, the decoding unit
17 reports a reception error state (850) and continues to determine
whether LOL and RXOOA alarm signals are generated.
[0065] Meanwhile, as shown in FIG. 6B, after operation 660, the
decoding unit 17 determines whether a RXOOA alarm signal is
generated (910). If no RXOOA alarm signal is generated, the
decoding unit 17 reports a SFI-5.2 interface mode state (990) and
continues to determine whether a RXOOA alarm signal is generated.
Meanwhile, if a RXOOA alarm signal is generated, the decoding unit
17 determines that SFI-5.2 reception does not normally operate,
activates the OTL3.4 RX interface unit 11 (920), and determines
whether a LOL alarm signal is generated by the OTL3.4 RX interface
unit 11 (930). Meanwhile, if no LOL alarm signal is generated, the
decoding unit 17 determines whether signals are normally received
from the OTL3.4 RX interface unit, activates the OTL3.4 TX
interface unit 14 and deactivates the SFI-5.2 RX and TX interface
units 10 and 13 to thereby change data paths connected to the
SFI-5.2 RX and TX interface units 10 and 13 to the OTL3.4 RX and TX
interface units 11 and 14, respectively (940). After operation 940,
the decoding unit 17 continues to determine whether a LOL alarm
signal is generated (610).
[0066] Meanwhile, if a LOL alarm signal is generated in operation
930, the decoding unit 17 determines whether a RXOOA alarm signal
is generated by the SFI-5.2 RX interface unit 10 (950). At this
time, if no RXOOA alarm signal is generated, the decoding unit 17
deactivates the OTL3.4 RX interface unit 11 (980). Meanwhile, if a
LOL alarm signal is generated and no LOL alarm signal is generated
in operation 960, the decoding unit 17 activates the OTL3.4 TX
interface unit 14 (940). If a RXOOA alarm signal is generated and a
LOL alarm signal is generated in operation 960, the decoding unit
17 reports a reception error state (970) and continues to determine
whether RXOOA and LOL alarm signals are generated.
[0067] Various examples of a transmission apparatus and method for
serial and parallel channel interworking to support signal
comparability between serial and parallel channel optical modules
using a 40 GBASE-FR PMD optical module supporting a SFI-5.2
interface, have been described with reference to FIGS. 3 through
6B. However, 40 G Ethernet signals can be transmitted, without
having to use a SFI-5.2 interface, if the 40 GBASE-FR optical
module includes only a multiplexer and a demultiplexer.
Accordingly, in order to miniaturize a 40 GBASE-FR optical module
and minimize power consumption, signal comparability between
optical modules needs to be provided without having to support a
SFI-5.2 interface.
[0068] Actually, CFP and QSFP+ types of 40 GBASE-LR4 optical
modules that transmit signals using four wavelengths have been
released or are expected to be released, however, the CFP and QSFP+
optical modules do not support the SFI-5.2 interface. That is, even
pins of a connector for the SFI-5.2 interface have not been
defined, and the QSFP+ optical module includes no extra pins for
defining such additional pins. Accordingly, when the 40 GBASE-FR
optical module which does not support the SFI-5.2 interface is
used, comparability between the 40 GBASE-FR optical module and a 40
G 300 pin MSA optical module is not ensured. Before describing a
configuration of the present invention for overcoming the problem,
a connection structure between a 40 GBASE-FR optical module and an
OTL3.4 interface unit of a general transmission apparatus for
serial and parallel channel interworking will be described.
[0069] FIG. 7 is a diagram illustrating a 40 G OTL3.4 RX interface
11 of a general transmission apparatus 72 for serial and parallel
channel interworking that interfaces a 40 GBASE-FR optical module
70.
[0070] Signals that are input from a 40 G 300 pin MSA optical
module to the 40 GBASE-FR optical module 70 are transmitted in the
transmission order of OTU3 frames, and the 40 GBASE-FR optical
module 70 demultiplexes an OTU3 frame signal through a 1:4
demultiplexer 710 and transmits the resultant signal to the
transmission apparatus 72. At this time, skews are generated in
four RX data lanes, and skews also may be generated in OTL3.4 lane
receivers 76 of the transmission apparatus 72 according to the
reception characteristics of the OTL3.4 lane receivers 76 when the
OTL3.4 lane receivers 76 receive data. The signals input to the
OTL3.4 lane receivers 76 are not only OTL3.4 signals but also
signals having skews, and if the OTL3.4 lane receivers 76 receive
the signals, the OTL3.4 lane receivers 76 cannot detect a Frame
Alignment Sequence (FAS) signal for each OTL3.4 lane. If such skews
generated in the reception direction cannot be compensated for, the
transmission apparatus 72 may not receive OTU3 signals
normally.
[0071] Also, skews are generated from the OTL3.4 RX interface unit
73 to the 40 GBASE-FR optical module 70 through four data lanes
TXDATA[3:0], and skews may be generated when data signals are
received through the four data lanes TXDATA[3:1] according to the
characteristics of a 4:1 multiplexer (MUX) 700. If such skews
generated in the transmission direction cannot be compensated for,
the 40 G 300 pin MSA optical module may not receive OTU3 signals
normally.
[0072] As such, in order to maintain comparability with the 40 G
300 pin MSA optical module, it is necessary to compensate for
reception and transmission skews generated between the 40 GBASE-FR
optical module 70 and the transmission apparatus 72 for serial and
parallel channel interworking and to realign the skew-compensated
signals to OTN transmission signals.
[0073] In order to implement comparability with signals input to
the transmission apparatus 72 from a 40 G 300 pin MSA optical
module through the 40 GBASE-FR optical module 70, when OTU3 signals
received serially are 1:4 demultiplexed, data signals output
through four data lanes will be described with reference to FIG.
8.
[0074] FIG. 8 shows four data signal streams that are generated by
1:4 demultiplexing of a serial OTU3 signal.
[0075] In drawings that will be described below, it is assumed that
a 40 GBASE-FR optical module includes no additional logic, such as
a SFI-5.2 interface unit or an OTL3.4 interface unit, for
compensating for skews of four data lanes or for generating a
signal for compensating for the skews.
[0076] Referring to FIG. 8, if a 40 G serial signal is input from a
40 G 300 pin MSA optical module to a 40 GBASE-FR optical module in
the transmission order of OTU3 frames, the 40 GBASE-FR optical
module demultiplexes the 40 G serial signal into four 10 G signals
through a 1:4 multiplexer. A frame alignment signal of an OTU3
frame has been defined as 6 bytes of A1A1A1A2A2A2 (A1=Xf6, A2=x28).
Accordingly, if a frame alignment sequence is 1:4 demultiplexed, a
specific pattern of 12 bits for each of the four data lanes is
repeated per OTU3 frame period/4.
[0077] That is, according to an example, by adding a configuration
for 1:4 demultiplexing pattern alignment as well as an OTL3.4 lane
alignment unit to the transmission apparatus for serial and
parallel channel interworking, it is possible to compensate for and
align skews for each of the four data lanes so as to receive the
OTU3 frame signal of the 40 G 300 pin MSA optical module.
[0078] In detail, as shown in FIG. 8, the OTU3 frame signal is
received from a 40 G 300 pin MSA optical module to a 40 GBASE-FR
optical module in the transmission order of OTU3 frames. At this
time, the 40 GBASE-FR optical module performs 1:4 demultiplexing on
the OTU3 frame signal to generate four lane data signals. xF6, xF6,
xF6, x28, x28, and x28 signals which are the FASs of the OTU3 frame
are received repeatedly for each OTU3 frame period. Four lane data
signals are generated through a 1:4 demultiplexer, and skews are
generated according to the characteristics of the 1:4 demultiplexer
when the four lane data signals are output, so that the skews are
generated between the four data lanes to the transmission apparatus
for serial and parallel channel interworking. However, when signals
received in the transmission order of OTU3 frames are 1:4
demultiplexed, different patterns of periodic signals are generated
in the respective four data lanes. That is, as shown in FIG. 8,
xA95 may be used as an alignment bit signal for a first lane of the
OTU3 frame, xFC0 may be used as an alignment bit signal for a
second lane of the OTU3 frame, xFEA may be used as an alignment bit
signal for a third lane of the OTU3 frame, and xA800 may be used as
an alignment bit signal for a four lane of the OUT3 frame.
Accordingly, the current example uses an OTU3 demultiplexing lane
receiver that detects OTU3 demultiplexing patterns xA95, xFCO.sub.3
xFEA, and xA80, instead of a FAS pattern detector for each OTL3.4
lane. In this case, it is possible to measure skew values between
the individual lanes and compensate the skews through alignment bit
signals that are periodically repeated for the respective data
lanes. Also, since the alignment bit signals are different for the
respective data lanes, the lanes may be realigned according to
detected alignment bit signals. Hereinafter, a transmission
apparatus for 40 G serial and parallel channel interworking,
including an OTU3 demultiplexing lane receiver, will be described
with reference to FIG. 9.
[0079] FIG. 9 is a diagram illustrating a configuration example of
a receiver of a transmission apparatus for 40 G serial and parallel
channel interworking that does not support the SFI-5.2
interface.
[0080] Referring to FIG. 9, the receiver of the transmission
apparatus for 40 G serial and parallel channel interworking
configures an OTU3 DEMUX RX interface unit 90, instead of the
OTL3.4 RX interface unit 73 of FIG. 7, in order to receive signals
of a 40 G 300 pin MSA optical module through a 40 GBASE-FR optical
module. The OTL3.4 lane receivers 76 of FIG. 7 detects a FAS
pattern for each OTL3.4 lane and uses the detected FAS pattern to
compensate for skews generated between the OTL3.4 lane and another
OTL3.4 lane, whereas since OTU3 DEMUX lane receivers 92 of FIG. 9
can detect all OTU3 DEMUX patterns xA95, xFC0, xFEA, and xA80, the
OTU3 DEMUX lane receivers 92 can detect all input patterns of xA95,
xFC0, xFEA, and xA80. Also, the OTU3 DEMUX lane receivers 92 align
data according to the detected pattern, and transfer a signal about
a timing at which a pattern of each lane has been detected and
about which pattern is the detected pattern to an OTU3 DEMUX Deskew
controller 94. The OTU3 DEMUX Deskew controller 94 may generate
timing signals for minimizing delays in data outputs of delay units
96, based on timings at which the patterns of the individual lanes
have been detected, received from the individual OTU3 DEMUX lane
receivers 92. Also, the OTU3 DEMUX Deskew controller 94 may decide
an order of the lanes and realign the lanes according to the
decided order based on information about which patterns are
detected in the lanes. If the same pattern is detected in two or
more lanes, this means that signals are abnormally received.
Accordingly, in this case, the OTU3 DEMUX Deskew controller 94
determines that an error has generated in alignment of the lanes
and may inform a user of the fact of the error generation.
[0081] According to an example, the transmission apparatus for 40 G
serial and parallel channel interworking may configure an OTU3
DEMUX RX interface unit 90 of FIG. 9, separately from the OTL3.4 RX
interface unit 73 of FIG. 7. According to another example, the
transmissions apparatus for 40 G serial and parallel channel
interworking may configure the OTU3 DEMUX RX interface unit 90 by
changing the configuration of the OTL3.4 lane receivers 76 to the
configuration of the OTU3 DEMUX lane receivers 92 of FIG. 9 and the
configuration of the OTL3.4 deskew controller 78 to the
configuration of the OTU3 DEMUX Deskew controller 94 of FIG. 9.
That is, it is possible to change the function of the OTL3.4 RX
interface unit 73 such that the OTL3.4 RX interface unit 73 detects
OTU3 DEMUX patterns xA95, xFCO, xFEA, and xA80, instead of
detecting and aligning frames with FAS patterns of frame
signals.
[0082] Also, since a lane rotator is used in an OTL3.4 interface
and not used in an OTU3 transmission method, the OTU3 DEMUX RX
interface unit 90 needs no lane rotator and accordingly the example
of FIG. 9 includes no lane rotator. However, as shown in FIG. 10
which will be described later, it is also possible to bypass a lane
rotator using a lane rotator selector.
[0083] Also, the OTU3 DEMUX lane receivers 92 may sequentially
detect the patterns of Xa95, xFCO, xFEA, and xA800, instead of
detecting FAS patterns in the OTL3.4 lane receivers 76. At this
time, since the OTU3 DEMUX lane receivers 92 do not simultaneously
detect all the four patterns of xA95, xFCO, xFEA, and xA800, a more
or less long time is taken to detect all the four patterns of xA95,
xFCO, xFEA, and xA800. However, since patterns to be compared for
each time period are corrected, the OTU3 DEMUX lane receivers 92
can be manufactured with a logic capacity that is smaller than that
of a logic for sensing four patterns.
[0084] FIG. 10 is a diagram illustrating another configuration
example of receivers of a transmission apparatus for 40 G serial
and parallel channel interworking that does not support the SFI-5.2
interface.
[0085] Referring to FIG. 10, the receivers of the transmission
apparatus for 40 G serial and parallel channel interworking include
an OTU3 DEMUX & OTL3.4 RX interface unit 100 including OTL3.4
lane receivers 76 and OTU3 DEMUX lane receivers 92. Also,
additionally, the receivers include a RX lane rotator 102 to select
one of an OTL3.4 RX interface function and an OTU3 DEMUX RX
interface function through a bypass function.
[0086] As described above with reference to FIGS. 9 and 10, if a 40
GBASE-FR optical module that does not support a SFI-5.2 interface
receives a serial OTU3 signal from a 40 G 300 pin MSA optical
module, the 40 GBASE-FR optical module 1:4 demultiplexes the serial
OTU3 signal to generate four lane data signals, and if a
transmission apparatus for 40 G serial and parallel channel
interworking receives the four demultiplexed lane data signals from
the 40 GBASE-FR optical module, the receivers of the transmission
apparatus compensate for skews of the four lane data signals and
aligns the resultant data signals to normally receive OTU3
signals.
[0087] However, it is impossible to provide signal comparability
between the 40 GBASE-FR optical module and the 40 G 300 pin MSA
optical module only through the receivers. That is, in order for
the 40 G 300 pin MSA optical module to receive OTU3 frame signals
in the transmission order of OTU3 frames, as in the SFI-5.2
interface unit, it is necessary to compensate for skews generated
between the 4:1 multiplexer of the 40 GBASE-FR optical module and
the transmitter of the transmission apparatus for 40 G serial and
parallel channel interworking.
[0088] Hereinafter, an example of a transmission apparatus for 40 G
serial and parallel channel interworking, which does not support
the SFI-5.2 interface, to compensate for skews generated between a
multiplexer and demultiplexer of the 40 GBASE-FR optical module and
a transceiver of the transmission apparatus will be described with
reference to FIG. 11, below.
[0089] FIG. 11 is a diagram illustrating a configuration example of
a transceiver of a transmission apparatus 1e for 40 G serial and
parallel channel interworking that does not support the SFI-5.2
interface.
[0090] Referring to FIG. 11, the transmission apparatus 1e for 40 G
serial and parallel channel interworking includes four TX delay
units 114, a TX lane rotator 116, and an OTU3 TX pre-skew
controller 118, in order to compensate for skews generated between
a 4:1 multiplexer of a 40 GBASE-FR optical module 111 and a
transmitter 110 of the transmission apparatus 1e. The 40 GBASE-FR
optical module 111 may be, as illustrated in FIG. 11, configured
with a chip such that the 4:1 multiplexer and a 1:4 demultiplexer
can be looped back.
[0091] As described above with reference to FIG. 10, if the
receivers of the transmission apparatus 1e receive OTU3 frame
signals through a 1:4 DEMUX pattern alignment unit, it can be
recognized that the OTU3 frame signals are signals received from a
40 G 300 pin MSA optical module. Accordingly, the transmitter 110
of the transmission apparatus 1e is converted from an OTL3.4 mode
to an OTU3 transmission mode.
[0092] When the transmitter 110 has been converted to an OTU3
reception and transmission mode, the 40 GBASE-FR optical module 111
loops backs four data lane signals input to the 4:1 multiplexer of
the 40 GBASE-FR optical module, or loops back serial signals output
after 4:1 multiplexing to the 1:4 demultiplexer. The 4:1
multiplexer and the 1:4 demultiplexer loop backs the four data lane
signals in the direction of the transmission apparatus 1e for 40 G
serial and parallel channel interworking so that the transmission
apparatus 1e can receive the four data lane signals which the
transmission apparatus 1e has transmitted.
[0093] According to an example, if reception of OPU3 signals
normally operates and the transmitter 110 is converted into the
OTU3 signal transmission mode, the receiver 112 fixes the RX delay
units 113 that have already compensated for skews to prevent skews
from being again compensated for. In this case, since the 4:1
multiplexer and the 1:4 demultiplexer have looped backs signals,
the receiver 112 again receives signals output from the transmitter
110, and skews of four data lanes between the 1:4 demultiplexer and
the receiver 112 have been compensated for through the RX delay
units 113.
[0094] However, since skews between four data lanes between the 1:4
multiplexer and the transmitter 110 of the 40 GBASE-FR optical
module 111 are not compensated for, if loop-back is performed, the
receiver 112 can detect no signal due to skews between the data
lanes. Accordingly, the receiver 112 operates the TX pre-skew
controller 118 to adjust the TX delay units 114, while fixing the
RX delay units 113.
[0095] That is, the amount of skews generated in the four lanes
from the 1:4 demultiplexer to the transmission apparatus 1e for 40
G serial and parallel channel interworking has been compensated for
by the receiver 112, and the remaining amount of skews generated in
the four lanes from the transmitter 110 to the 4:1 multiplexer can
be compensated for by the TX pre-skew controller 118.
[0096] If skews are compensated for through the TX pre-skew
controller 118 and transmission delay units 114 of the transmitter
110 and patterns are normally aligned, the loop-back of the 40
GBASE-FR optical module 111 is released so that signals are
normally transmitted to and received from the 40 GBASE-FR optical
module 111. Accordingly, since skews between the 4:1 multiplexer
and the transmitter 110 of the 40 GBASE-FR optical module 111 have
been compensated for, signals output to the 40 GBASE-FR optical
module 111 have signal comparability with a 40 G 300 pin MSA
optical module.
[0097] Meanwhile, data is looped back and converted into data that
is input to a transmission clock of the system, not to a reception
clock that receives data, according to the characteristics of Giga
transceivers used in the transmitter 110 and receiver 112 of the
transmission apparatus 1e or according to the characteristics of
Giga transceivers used in the multiplexer and demultiplexer of the
40 GBASE-FR optical module 111, so that an amount of skews
generated between the 1:4 demultiplexer and the receiver 112 of the
40 GBASE-FR optical module 111 that will operate as a reception
clock may have a difference from that of when it operates as a
transmission clock. If such a difference is generated, skews
generated between the 4:1 multiplexer and the transmitter 116 can
be accurately compensated for, and accordingly operation for
accurate skew compensation can be added. An apparatus for
performing the operation for accurate skew compensation will be
described with reference to FIG. 12, below.
[0098] FIG. 12 is a diagram illustrating another configuration
example of a transceiver of a transmission apparatus if for 40 G
serial and parallel channel interworking that does not support the
SFI-5.2 interface.
[0099] Referring to FIG. 12, the transmission apparatus if uses a
clock signal and RX data extracted from a 40 G serial signal
received from a 40 GBASE-FR optical module 121 to compensate for
skews generated between a receiver 122 and a 1:4 demultiplexer of
the 40 GBASE-FR optical module 122. Successively, the 40 GBASE-FR
optical module 121 generates a PRBS (PseudoRandom Binary Sequence)
or an iterative pattern through a PRBS generator 125, and
simultaneously outputs the PRBS and the iterative pattern to four
lanes, using a transmission clock signal of the system, instead of
a clock signal from a data signal received from the 1:4
demultiplexer.
[0100] Successively, the PRBS deskew controller 129 determines
whether the PRBS or iterative pattern of the four lanes input
according to the skew-compensated amount of skews has the same
pattern at the same timing. If the PRBS or iterative pattern has
the same pattern every clock, the PRBS deskew controller 129
determines that the skews have been compensated for regardless of
RX and TX clock signals. Meanwhile, if the PRBS or iterative
pattern that are received from the four lanes are not the same
pattern, the PRBS deskew controller 129 adjusts the RX delay units
123 in a unit of bit to re-compensate for skews according to the
changed amount of skews. By using the PRBS or iterative pattern
created by the PRBS generator 125 through the above-described
process, skews generated between the 1:4 demultiplexer and the
receiver 122 of the transmission apparatus if for 40 G serial and
parallel channel interworking are compensated for.
[0101] Thereafter, by looping back four lane signals that are input
to a 4:1 multiplexer through a transmission clock signal, again
inputting the resultant lane signals to the transmission apparatus
1f, and then adjusting TX delay units 124 of the transmitter 120 of
the transmission apparatus 1f, skews generated between the 4:1
multiplexer and the transmission apparatus if may be accurately
compensated.
[0102] A number of examples have been described above.
Nevertheless, it will be understood that various modifications may
be made. For example, suitable results may be achieved if the
described techniques are performed in a different order and/or if
components in a described system, architecture, device, or circuit
are combined in a different manner and/or replaced or supplemented
by other components or their equivalents. Accordingly, other
implementations are within the scope of the following claims.
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